Duct structure for gas-turbine engines



Aug. 11, 1953 HAWORTH 2,643,353

DUCT STRUCTURE FOR GAS-TURBINE ENGINES Filed May 4, 1951 s Sheets-Sheet 1 ]Za 7 2 y;

15% Z? Zg ATTORNEYS Aug. 11, 1953 HAWORTH DUCT STRUCTURE FOR GAS-TURBINE ENGINES 6 Sheets-Sheet 2 Filed May 4, 1951 Aug. 11, 1953 wo 2,648,353

DUCT STRUCTURE FOR GAS-TURBINE ENGINES Filed May 4, 1951 6 Sheets-Sheet 3 //VI//VTOH 3y LIONEL HA WORTH Aug. 11, 1953 HAWORTH DUCT STRUCTURE FOR GAS-TURBINE ENGINES 6 Sheets-Sheet 4 Filed May 4, 1951 Aug. 11, 1953 HAWORTH DUCT STRUCTURE FOR GAS-TURBINE ENGINES 6 Sheets-Sheet 5 Filed May 4, 1951 m/z/m/mfi L/DIVEL HA WORTH Aug. 11, 1953 L. HAWORTH DUCT STRUCTURE FOR GAS-TURBINE ENGINES 6 Sheets-Sheet 6 Filed May 4, 1951 Patented Aug. 11, 1953 DUCT STRUCTURE FOR GAS -TURBIN E ENGINE S Lionel Haworth, Littleov Rolls-Royce Limited, company er, England, assignor to Derby, England, a British Application May 4, 1951, Serial No. 224,509 In Great Britain May 17, 1950 17 Claims. 1

This invention relates to gas-turbine engine structures and is concerned with an annular duct structure of an engine comprising an inner wall, an outer tubular wall and strut members by which one wall is supported from the other coaxial wall of the duct. The strut members extend across the annular duct formed by the inner and outer Walls. Such a structure will hereinafter be referred to as a gas-turbine engine working fluid duct structure of the type specified, and the wall part which is supported from the other coaxial wall part will be referred to as a wall part of the type specified.

One example of a gas-turbine engine working fluid duct structure of the type specified is the exhaust assembly of an axial-flow turbine, which commonly comprises a substantially conical fairing co-operating with an outer tubular wall to form an annular exhaust passage which at one end registers with the turbine outlet annulus.

Various means have been provided for supporting Wall parts of the type specified from the coaxial wall and one such means comprised a series of tubular struts arranged at an angle to one another and arranged to extend across the working fluid passage from one part to the other. Where such a supporting arrangement is provided it is usual to enclose the supporting struts in aerofoil shaped fairings.

This invention has for an object to provide a novel construction of a gas-turbine engine working fluid duct structure of the type specified, whereby the overall weight of the structure may be reduced and manufacture facilitated.

According to this invention a gas-turbine engine working fluid duct structure of the type specified comprises a wall part of the type specified formed as a unit with strut members by which it is supported from a co-axial wall structure, and the wall-and-strut structural unit is formed from a number of similar sheet-metal pressings, each of which pressings provides a portion of each of a pair of adjacent aerofoil-section strut members, each of which portions affords a circumferentially-directed strut surface, and the segmental portion of the wall part which extends between and interconnects said adjacent strut members.

Preferably each pressing comprises the whole of one circumferentially-directed face of each strut from the leading edge of the aerofoil section to the trailing edge thereof, so that when the pressings are brought together in assembly they may be welded together or otherwise bonded over abutting leading and trailing edges of the strut portions and also over abutting axial continuations of these edges along the surface of the wall portion.

In the above preferred arrangement it will be seen that a wall part of the type specified has formed as a unit with it a series of sheet-metal aeorfoil-section fairings which can act as the supporting struts for the wall part, and the shape of each pressing from which the unit is formed may be considered as the shape obtained by cutting the wall-and-strut structure into a number of parts along axial planes which contain the leading and trailing edges of the aerofoil fairings.

Preferably, according to a feature of this invention, each pressing may comprise at the free end of each aerofoil-section strut, an end wall portion which, when the unit is supported from a coaxial wall, lies close to the surface of said coaxial wall. This end wall portion provides a convenient means for connecting the unit with the coaxial wall. For instance, the abutting end wall portions of adjacent pressings may be cut away to afford an aperture to receive a collar in which is engaged a spigot carried on the coaxial wall, so that the unit is located with respect to the coaxial wall but is capable of relative expansion thereto.

The invention has an important application in exhaust assemblies for axial-flow turbines and may be applied with advantage in the construction of the substantially conical fairings such as are commonly employed with such exhaust assemblies.

The application of the invention in such an exhaust arrangement will now be described in detail by way of illustration of the invention, reference being made in the description to the accompanying drawings, in which Figure l is a view of a gas-turbine engine having an exhaust arrangement embodying the invention,

Figure 2 is a View on the line 2-2 of Figure 1,

Figure 2A is a perspective view of the exhaust arrangement of Figure 2 with parts broken away,

Figure 3 is an axial sectional view of an alternative construction of exhaust arrangement to that shown in Figure 2, the section being on the line 3-3 of Figure 4,

Figure 4 is a section on the line 4Ll of Figure 3,

Figure 5 is an axial view on one of the pressings forming part of the arrangement of Figures 3 and 4,

Figure 6 is a view in the direction of arrow 5 (Figure 5) of the pressing shown in Figure 5, and

Figure 7 is a view similar to Figure 4 showing a modification.

Referring to Figure 1, there is illustrated a conventional gas-turbine engine of the reaction propulsion type. The engine illustrated comprises a compressor l0, combustion equipment i i connected to receive compressed air from the compressor IE to have fuel burnt in it; and an axialflow turbine l2 connected to receive the products of combustion from the combustion equipment I i, The turbine comprises a turbine rotor; 42a, drivingly connected to the'rotor of the compressor ID by a shaft i5, and a turbine casing I21).

The engine illustrated also comprises an exhaust assembly I3 supportedfrornthe turbine casing l2b. The exhaust assembly is of the kind comprising an outer tubular duct wall I3a, one end of which is securediibyaboltingzfiange l3b to the outlet end of the-turbine casing 121) and which may be cylindrical or vary in diameter, for instance may haveta taper-so. as to be frusto-conical, and a conical bullet-Msupported coaxially within the outer wall 13a to form an annular exhaust gas passage leading from the turbine outlet. The wall l3a has a bolting-flange We at its outletendibyawhicha jet pipe and propelling nozzle maybe secured in place.

The conical bullet'is supportedfrom thev outer wall ISa of the exhaust assembly, and in this embodiment is made up from four sheet-metal pressings Ma, Mb, i' lc, Hid which are so shaped that the bullet M is formedas a unitwith four aerofoil-section struts l6 which extend across the annular exhaust duct formed between the outer wall 13a and the conical bullet M, the combinedbullet and strut unit being attached to the outer wall-l=3a of the exhaust assembly through the outer ends of the struts 16.

It will be seen from-Figuresl and 2 that each ofthe sheet'metal pressings [4a, l ib, Me, Md comprises three essentialport-ions, whereof two portions 16a, I613 are eachformed as'half of an aerofoil-section strut *IS and-thethird portion is that quarter-of the conical bullet M which interconnects the strut portions lfia, 16b. The two strut portions Isa, 162) thus afford facing circumferentially directed surfaces of a pair of adjacent struts. Each pressing also includes an end portion l'fic'ior'the outer end of each strut portion-(6a, I612. The pressings Ma, Mb, I4c, l i'dare assembled-together withtheir edges in abutment and are conveniently welded together as indicated at'll so that the weld is effected along the leading and trailing edges of the struts I16 and along lines on the conical surface .of the'bullet l4 and on the surfaces of the end portions .lSc-of the struts which are continuations of and are in this case in the same axial plane as the leading and trailing edges of the struts l6. Theend portions [60 of the struts l6 are formed with apertures l8 which are engaged byradial pegs or spigots .IB mounted on the wall l-3aso that .the combined-bullet and strut unit is centrally located within the Wall l3a.but,is free to expand radially with respect to it.

The base of theconical bullet I4 isclosed by a sheet metal plate 20.

It will be appreciated that the number of struts lB-may be varied and also-that the pressings which have the strut portions formed in one with them need not, when secured together, afford the wholeof the surface of the conical bullet M.

For instance, referring to Figures 3 and 6, there is illustrated an arrangement in which there are threepressings 4a, I-Mb, I [40 each having portions lEa, 1-61) affording facin circumferentially-directed surfaces of adjacent struts 16, the central-planes of which struts 16 .4 are, as will best be seen from Figures 3 and 5, inclined to one another at In this construction, moreover, the part conical portion afforded by each pressing does not include the apex 'of the cone ..arid. in' this particular arrangement a small substantially conical cup 2| is secured in positon in the aperture left when the three pressings ll la, ll4b, H40

.aresecured together to close the aperture and toprovide the apex of the conical bullet 14.

In this construction moreover the base of the conical bullet-is closed by a sheet-metal pressing E20 which-isdished and has a peripheral corrugation l20a "for strengthening purposes.

As --in the previously described construction, thefi'eeends of the strut portions iGa, IBb are provided with an end portion I60 and the combinedconical bullet and strut unit is supported from the wall i3a by substantially radial pegs engaging in holes formed'by registering semicircular notches [8a (Figures 5 and 6) in-the abutting edges of the end portions 'l'6c. -'Conveniently afianged-sleeve-22 is fitted in the-hole formed bytheregistering notches F811 and the sleeve hasa cylindrical liner 23 fitted in it. The liner 23 is engaged by a spigot -likeplug 2 4 having at its outer-end a fiange 24'aby which the spigotlike plug 24-maybe'bolted to *a'flat ring 25. The ring 2.5 is convenientlyformed with internally threaded bosses "25a to receive -'the plug-retaining setscrews' 26,"andis'- itself "welded to the periphery of an aperturein'adished sheetmetal patch 2'! mounted on the outer'wall 13a of the exhaust assembly above a'zhole' za'in'the outer wall l3a.

A similar arrangement to that illustrated in Figures 3 to'6 is'illustrated'frn Figure 7. In the arrangement shown in Figurelyhoweverjnot only do the pressings which combine'both portions of the conical bullet and supporting struts it, terminate short of the .apex end ofthe conical bullet but also terminate short ofthe base end of the conical bullet. "Thepressings such as the pressing '2l4'a terminate just upstream of the strut portions and thebase end, of, the conical bullet is'formedby an.annular sheet-metal member '2 Mac, the upstream end of whichreceives the base $20 of the conical bulletand the downstream end of which overlaps,.as indicated .at 29, the upstream edges of thepressingssuchas thepressing 2l4a. The pressings suchasthe pressing 2 Ma. and the.annulansheet-metetlmember 2l4cc are conveniently welded together at the overlap 29.

In this construction moreoverthe outer wall of the exhaust assemblyisformeddn.two.parts or" which a part ll3a extendsaaxially substantially to the same extent asdothe pressings. such as the pressingi l4a, and.of whichtheipartetflb extends from r the upstream .end-of the exhaust assembly substantiallyrto .the upstream .endof the pressings. The'parts l,l3a,H-3b-over1ap, as indicated at38, and .are welded-together ,at -i this point.

The construction-described withreference to Figure '7 is especially suitable-for exhaust assemblies in which-the exhaust -gases .on leaving the turbine are turned to 'flow in a direction at an angle tothe-turbineaxis.

From the foregoing-description it will be-seen that each sheet-metal; pressing, such as the pressings Ma, Mb, Mo, mm, .the pressings N40,, 1 Mb, I Hi0 and the pressingssuchas -.the .pressing 2 Ma, may 1 each be considered i as :affording that portion of the combined conical bulletyand strut unit which is contained between a pair of axial planes drawn through the leading and trailing edges of a pair of adjacent struts It at least for the axial extent of the struts I6.

Moreover, it will be seen that the invention provides a simple unit comprising both a working fluid duct wall and struts for supporting the wall, which unit is easy to manufacture and can be supported from a coaxial wall in a simple manner. The construction of the invention also enables a substantial saving in the weight of a structure embodying the invention as compared with known arrangements.

I claim:

1. An exhaust duct structure comprising an outer tubular wall and an inner wall unit supported coaxially within said outer tubular wall; said inner wall unit affording an annular wall to cooperate with said outer tubular wall to define therebetween an annular fluid passage, and a plurality of struts extending outwardly across said passage from said annular wall to said outer tubular wall; and said inner wall unit comprising a plurality of metal pressings equal in number to said plurality of struts, each said pressing providing in one piece that portion of the annular wall which interconnects an adjacent pair of said struts and a portion of each of said adjacent pair of said struts, and integral joints interconnecting said metal pressings.

2. An exhaust duct structure comprising an outer tubular wall and an inner wall unit supported coaxially within said outer tubular wall; said inner wall unit affording an annular wall to cooperate with said outer tubular wall to define therebetween an annular fluid passage, and a plurality of struts extending outwardly across said passage from said annular wall to said outer tubular wall; and said inner wall unit comprising a plurality of metal pressings equal in number to said plurality of struts, each said pressing providing in one piece that portion of the annular wall which interconnects an adjacent pair of said struts and a portion of each of said adjacent pair of said struts, and weld metal interconnecting said pressings.

3. An exhaust duct structure comprising an outer tubular wall and an inner wall unit supported coaxially within said outer tubular wall; said inner wall unit affording an annular wall to cooperate with said outer tubular wall to define therebetween an annular fluid passage, and a plurality of struts extending outwardly across said passage from said annular wall to said outer tubular wall; and said inner wall unit comprising a plurality of metal pressings equal in number to said plurality of struts, each said pressing providing in one piece that portion of the annular wall which interconnects an adjacent pair of said struts and a portion of each of said adjacent pair of said struts, and integral joints interconnecting said metal pressings; and means for positioning said inner wall unit from said outer tubular wall comprising peg means mounted on the outer tubular wall and engaging in apertures in the outer ends of said struts.

4. An exhaust duct structure as claimed in claim 3, wherein the apertures in the outer ends of the struts are fitted with sleeve members slidingly to receive the peg means.

5. An exhaust duct structure comprising an outer tubular wall and an inner wall unit supported coaxially within said outer tubular wall; said inner wall unit affording an annular wall to cooperate with said outer tubular wall to define therebetween an annular fluid passage, and a plurality of aerofoil cross-section struts each having leading and trailing edges and a pair of oppositely and circumferentially-facing surfaces extending from its leading edge to its trailing edge and each extending outwardly across said passage from said annular wall to said outer tubular wall; and said inner wall unit comprising a plurality of metal pressings equal in number to said plurality of struts, each said pressing pro-- viding in one piece that portion of the annular wall which interconnects an adjacent pair of said. struts and that circumferentially-facing surface of each of said adjacent pair of said struts which faces the other of said adjacent pair of said struts, and integral joints interconnecting said pressings.

6. An exhaust duct structure comprising an outer tubular wall and an inner wall unit sup ported coaxially within said outer tubular wall; said inner wall unit affording an annular wall to cooperate with said outer tubular wall to define therebetween an annular fluid passage, and a plurality of aerofoil cross-section struts each having leading and trailing edges and a pair of oppositely and circumferentially-facing surfaces extending from its leading edge to its trailing edge and each extending outwardly across said passage from said annular wall to said outer tubular wall; and said inner wall unit comprising a plurality of metal pressings equal in number to said plurality of struts, each said pressing providing in one piece that portion of the annular Wall which interconnects an adjacent pair of said struts and that circumferentially-facing surface of each of said adjacent pair of said struts which faces the other of said adjacent pair of said struts, and weld metal interconnecting said pressmgs.

'7. An exhaust duct structure comprising an outer tubular wall and an inner wall unit supported coaxially within said outer tubular wall; said inner wall unit aifording an annular wall to. cooperate with said outer tubular wall to define: therebetween an annular fluid passage, and a plurality of aerofoil cross-section struts each having leading and trailing edges and a pair of oppositely and circumferentially-facing surfaces extending from its leading edge to its trailing edge and an end surface, and each extending outwardly across said passage from said annular wall to said outer tubular wall with said end surface lying close to said outer tubular wall; and said inner wall unit comprising a plurality of metal pressings equal in number to said plurality of struts, each said pressing providing in one piece that portion of the annular wall which interconnects an adjacent pair of said struts, that circumferentially-facing surface of each of said adjacent pair of said struts which faces the other of the adjacent pair of struts, and a portion of the end surface of each of said struts, and integral joints interconnecting said pressings.

8. An exhaust duct structure comprising an outer tubular wall and an inner wall unit supported coaxially within said outer tubular wall; said inner wall unit affording an annular wall to cooperate with said outer tubular wall to define therebetween an annular fluid passage, and a plurality of aerofoil cross-section struts each having leading and trailing edges and a pair of oppositely and circumferentially-facing surfaces extending from its leading edge to its trailing edge and an end surface, and each extending outwardly across said passage from said annular wall. to said outer tubular wall with said end terconnects an-adjacent pairqofsaid struts, that circumferentially-facing surface'of each of said adjacent pair: of said struts whichfaces-the other of; the adjacent-pair-of -strutsi,and a portionof the .endsuriaceof eachiof: said struts, and1inte-- gral; joints interconnectingv .saidzpressings; comprising also meansto. position said sinnerwa-ll unit axially and ic-ircumferentially, within said outer tubular wall comprising peg 'means mounted on. said outer tubular .wall and engaging. aperturesin the .end surfacesuof-said struts;

, 9. -An--.exha-ust-duct1structure:asyclaimed in claim 8, wherein "the apertures insaid: end surfaces of; said struts. arewfitted with sleeves to he- ;slidingly' engaged with 'the peg neans l0. Anexhaust :duct structure ccmprising;.an outer tubular wall and ran innerawall uni-tsupportedcoaxially withinsaidouter tubular wall said inner wall unitaffording: :a conical wall to cooperate with said outer tubular; wall-to define therebetweenanannular fluid passage, and a plu-- .rality 10f struts :extending, outward-1y across said passages-from saidconical-1 wall to said outer tubular wall; 'andsaid inner wall unit comprising. a plurality of .metal pressings equal in number to said plurality. of-struts',each saidpressing. providing in one .piece that portionof. the: conical wall which interconnects; an adjacent; :pair :of" saidstruts and .a iportgionpf each of said adjacent pair'of .:sa;id struts; :and integral joints intercom; 1'

necting, saidrmetaL-pressin 11.1 An :exhaust:[ductstructure comprising an outer tubular wall and an inner wall unit sup-. ported icoaxiaily within said :outer. tubular. wall; said=.inn.er lwall 'unit. affording. a conical wall @110 cooperate i-withieaid outer; ztubular. wall .to definetherebetweennanpannular iluidpassaga. and a p urality; of: \struts: extending, outwardly across saidpassage; dromsaid :-conical-. wall to said outer tubular :wall a and said. inner wall unit comprising azpluralitypt metal; pressings equahinxnumber "to said plurality: .of --struts;:;each; said pressing. 'providin%iin. .0ne1 ipiecei that. portion ofxthe-iconicai wall which;interconnectsan zadjacent paiimof said- :str.uts .-and iportion; of each of said adja-.' cent. pair ofsaid struts, and. weld metal dnterconnecting said :pressings:v

12.; An rexhaust iduct structurecomprising, an outer atubular iwalfandnan inner wailz-umtssupr ported coaxially-within the eaten-tubular nvall; said .inner iwall unit affording .a (conical wall :to copei-ate...with said :outer tubular wall :tozdefine therebetween can annular. .fluid -.;.passage,. and a plurality of- :aeriofoil cross-section struts-each having-aleading; edge=,.a trailing edge, aapair of oppositely and .circumferentially-facing. surfaces extending-:from said leading edgetolsaidctrailing edge, and..an end-eurf-acerattheouterrend thereof, and-each said strut extending outwardly across said, annulartfluidipassage from said conical wall to said outer-tubular; wall with: the; end surface lying-.closeato said outer tubular wall; and said inner-wall unit comprising a .plurality of :metal pressings; equal; in. :nu-mber .to; said :pl-urality .of struts; each .saidipressing.,.=providing.sin -.one piece that portion f: 'saidxconical awall whichaintercorh nectsan adj acentpair of: said struts-,zthatzcircumferentially-f'acing; surface 1 'of each of: said adj acent-pairofssaidpz strut-s: which ;faces :the other. of said adjacent:painofisaidrstruts,randia portion Ill) of said end surface of each of said adjacent pair ofsaid struts, and weld metalinterconnecting said pressings. v

13. An exhaust duct structure as claimed in claim 12, wherein said conical wall terminates short of the apex of the cone and wherein the apex of the cone is formed by a conical cup secured to the narrower end of said conical wall 14. An exhaust duct structure as claimed in claim 12,. wherein the base end of said conical wall is afforded by an annular wall secured in.

overlapping relation to the adjacent ends of said pressings.

15. An exhaust duct structure comprising an outer tubular wall and. aninner wall unit supportedcoaxially withiin the outer tubular wall;

saidinner wall unit affording a conical wall .to-

cooperate with said outer tubular wall to define therebetween an annular fluid passage, and a plurality of aerofoil cross-section struts each having a leading edge, a trailing edge, a pair of oppositely-and circumferentially-facing surfaces extending from said leading edgeto said trailing edge, andan end surface at the outer end thereof, and-each said strut extending outwardly across saidiannular fluid passage from said conical.

wallto said outer tubular wall with the endsurface lying close to said outer tubular wall; andv said inner .wall unit comprising. a plurality of metal pressings equal in number tosaidplurality of struts, each said pressing providing in one piece that portion of saidconicalwall which interconnects an adjacent pair of said struts, that circumferentially-facing surface of each of said adjacent pair of saidv struts which faces the other of-said adjacent pair ofsaid struts, and a portionof said end surface of each of said adj,a-- cent pairofsaidstruts, and weld metal interconnecting said pressings; and .means to position said inner wall unit axially and circumferentially. with respect to said outer tubular wall comprising plugelements secured tosaidouter tubular wall and engaging. in apertures in said end surfaces of said struts.

l.6.-.-An exhaust duct structure as claimed. in claim 15, comprising also cylindrical liners fitted within-said-apertures in the end surfaces of said struts slidingly to receive said plug elements.

17.. Aworking fluid duct structure comprising arnouter tulcular wall and :an inner wall unit supported coaxially, within said outer tubular wall; said inner wall unit affording anannular wall to cooperate with said outer tubular wall to define therebetween an annular ifiuiduzpassage, and. -a plurality of struts extendingoutwardly acrosssaid passage from said annular wall to said outer 'tubularwall; andsaid inner wall unit comprising a plurality of metal pressings equal in number to saidplurality of struts, each said pressing providingin one piece that portion of theannular wall which interconnects an adjacent pair of saidstruts and aportion of each of said adjacentpair of said-struts, and-integral joints interconnecting said metal pressings.

LIQNEL HAVI ORTH.

ReferencesCited in the file Of this patent UNITED STATES PATENTS N umber 

